Process for breaking out an inner shape in a glass sheet

ABSTRACT

A break-out process includes scoring a cutting line in the surface of the glass using a cutting tool, which cutting line delimits the outer contour of the inner shape and the inner contour of a peripheral shape; bringing the peripheral shape of the glass sheet into contact with a bearing system along the outer contour of the inner shape; the use of a deformation system for deforming one of the inner shape and of the peripheral shape by convex bending toward the side opposite the cutting line. The differential deformation between the inner shape and the peripheral shape is sufficient to break out the inner shape along the cutting line and create the distance needed for the contactless extraction of the inner shape relative to the peripheral shape. The extraction is carried out while maintaining the convex bending.

The present invention relates to the field of breaking out an innershape in a glass sheet, for example with a view to forming an openingroof in a motor vehicle glazing that forms a roof or else for example apivoting glazed opening within a motor vehicle side glazing, such as oncertain sliding doors.

A first known technique consists in cutting out the inner shape by meansof a waterjet (FIG. 1a ). The waterjet produces a cut by removal ofmaterial between the inner shape and the main shape, which allows aneasy separation (FIG. 1b ). Nevertheless, the inner shape cannot bereused since, in order to be of good quality, the cut must begin insidethe inner shape (FIG. 1a ).

The inner shape must be cut out from another glass sheet (FIG. 1c ) inwhich the edges will have been broken off, before assembling the twocomplementary shapes (FIG. 1d ).

One drawback of this process is that the inner shape must be destroyed.In addition, the waterjet cutting process is slow.

Another faster process consists in using cutting with break-out.

There are two successive operations:

-   -   a preliminary operation of scoring one or more surface cracks in        the surface of the glass using, for example, a glass-cutting        wheel or a laser; these cracks form lines at the contours of the        shape; this operation is known as the “cutting” operation;    -   an operation of propagating the initial surface crack through        the thickness of the glass sheet; this operation is known as the        “break-out” operation and allows the shape that is to be cut out        to be separated from the initial glass sample known as the        blank.

FIGS. 2a and 2b illustrate the cutting via scoring then pressing on thesacrificial central portion in order to achieve the break-out.Additional cutting lines (FIG. 2a ) are then preferably provided inorder to facilitate the breaking-out of the various fragments of thecentral portion.

But this technique also has the drawback of destroying the inner shape.It is necessary to cut out and finish an inner shape (FIG. 2c ) fromanother glass sheet, and to assemble in fine the two complementaryshapes (FIG. 1d ).

One objective of the invention is to facilitate the cutting of an innershape in a glass sheet.

For this purpose, one subject of the invention is a process for breakingout an inner shape in a glass sheet intended to form a glazing,comprising:

-   -   a step of scoring a cutting line in the surface of the glass        using a cutting tool, which cutting line delimits the outer        contour of said inner shape and the inner contour of a        peripheral shape;    -   bringing the peripheral shape of the glass sheet into contact        with a bearing means along the outer contour of the inner shape;    -   the use of a deformation means for deforming one of the inner        shape and of the peripheral shape by convex bending toward the        side opposite the cutting line, the differential deformation        between the inner shape and the peripheral shape being        sufficient to break out the inner shape along the cutting line        and create the distance needed for the contactless extraction of        the inner shape relative to the peripheral shape, the extraction        being carried out while maintaining the convex bending.

This process makes it possible to retain the inner shape and to use itas an opening of complementary shape for the window made in the glasssheet. This reduces the production cost.

In addition, the process is fast.

This break-out technique also has the advantage of being able to beincorporated into an existing line.

According to particular embodiments, the process additionally has one ormore of the following features, taken alone or in any technicallypossible combination:

-   -   the process uses a holding means that counters the effect of the        deformation means in the other of the inner shape and of the        peripheral shape;    -   the bearing means extends over the entire outer contour of the        inner shape, inside, opposite or outside relative to the cutting        line;    -   the bearing means comprises two bearing members, preferably one        around the other;    -   the bearing means comprises at least one seal for forming at        least one low-pressure zone opposite at least one of the inner        shape and of the outer shape;    -   a low-pressure zone is a zone of convex bending deformation of        said one of the inner shape and of the peripheral shape, the        deformation means being a suction means;    -   a low-pressure zone is a holding zone that counters the        deformation of said other of the inner shape and of the        peripheral shape, the holding means being a suction means;    -   the bearing means is suitable for being used for bearing against        said other of the inner shape and of the peripheral shape during        the breaking-out of the inner shape;    -   the deformation means is or comprises a convex counter-form        suitable for pressing said one of the inner shape and of the        peripheral shape in convex bending.

Another subject of the invention is a machine for breaking out an innershape in a glass sheet intended to form a glazing, comprising:

-   -   a cutting tool and means for the automatic displacement of said        tool in order to produce a cutting line that delimits the outer        contour of said inner shape and the inner contour of a        peripheral shape;    -   a bearing means for bearing against the glass sheet along the        outer contour of the inner shape; and    -   a deformation means for deforming one of the inner shape and of        the peripheral shape by convex bending toward the side opposite        the cutting line, and carrying out the extraction of the inner        shape relative to the peripheral shape while maintaining the        convex bending of said one of the inner shape and of the        peripheral shape, with the deformation means and/or another        means for maintaining the convex bending.

The invention will be better understood on reading the followingdescription, given solely by way of nonlimiting example, with referenceto the following figures:

FIGS. 1a to 1d are schematic top views of a manufacturing process usingwaterjet cutting, according to the prior art;

FIGS. 2a to 2d are views similar to FIGS. 1a to 1d illustrating anothertechnique for extracting an inner shape according to the prior art, bycutting and break-out;

FIGS. 3 to 5 are schematic vertical cross-sectional views of varioussteps of a process according to one particular embodiment of theinvention;

FIGS. 6a to 6d, 7a to 7d and 8a to 8d are also schematic verticalcross-sectional views of the steps carried out during three differentbreak-out processes of a first embodiment and FIGS. 9a to 9d are similarfigures of an example of a second embodiment.

FIGS. 3 to 5 schematically illustrate a process according to oneparticular embodiment of the invention, consisting firstly of a step ofscoring a cutting line 2 (FIG. 3), that is to say of creating a crack ona first face 4A of the glass sheet 4, followed by a step of breaking outby convex bending of the inner shape.

It should be noted that, throughout the text, the term “inner shape” isunderstood to mean a shape, the contour of which is a closed line andwhich is on the inside with respect to the peripheral contour of theglass sheet.

It should also be noted that the glass sheet to be cut is typically a“blank”. In order to produce a blank, generally glass sheets ofrectangular or trapezoidal shape, which are referred to as “blanks”, arefirstly cut from jumbo or lehr-end size glass sheets. These are glasssheets having a shape which is a convex polygon containing the finalglazing to be produced while leaving around the entire perimeter a“trim” sufficient for carrying out the optional breaking-off of theedges. As a variant, it is a ready-to-shape glass sheet, i.e. the shapeof which corresponds substantially to the final shape of the glazing. Itis however, generally, a glass sheet of any suitable type, even if it ispreferably a flat glass sheet.

It should also be noted that the jumbo and lehr-end size glass sheetsare glass sheets obtained on the line for manufacturing a ribbon offloat glass.

The scoring of the cutting line is, for example, carried out using aglass-cutting wheel 8 or any other suitable cutting instrument, such asfor example a laser. The cutting line 2 is a crack intended to enablethe breaking along this line during the break-out step. It is thereforea partial cut, i.e. only over a portion of the thickness of the glasssheet. This is what a “cutting line” is understood to mean throughoutthe text.

FIGS. 4 and 5 illustrate the principle of the invention, namely breakingthe glass sheet along the cutting line 4 by convex bending of the innershape 6 (or alternatively of the peripheral shape 10 as illustrated inFIGS. 9a-9d and explained later on). This convex bending is carried outtoward the side opposite the side of the cutting line 4, i.e. downwardin the figures.

The peripheral shape 10 is itself maintained in its initial state, thedeformation thereof by bending being prevented (or only limited) by asuitable holding means, such as a suction means, associated with abearing means that bears the peripheral shape, as explained in greaterdetail below.

The differential bending of the inner shape 6 relative to the outershape 10, simultaneously over the whole of the contour of the innershape, achieves the break-out and makes it possible to separate theedges of the inner shape from the inner contour of the peripheral shape,which facilitates the extraction of the inner shape.

The extraction of the inner shape 6 is for example carried out in adirection opposite to that of the bending, as illustrated by FIG. 5 inwhich the extraction is carried out upward. This is, as a variant, anextraction of any suitable type, insofar as the shape being bent is keptbent during the extraction.

FIGS. 6a to 6d, 7a to 7d and 8a to 8d illustrate more specifically threemethods of implementing the invention, provided by way of example, andaccording to a first embodiment in which the inner shape 6 is bent.According to a second embodiment which will be explained with referenceto FIGS. 9a-9d , it is the peripheral shape 10 which is bent.

In the example from FIGS. 6a to 6d , just like in all the other examplesfrom FIGS. 7a-9d , a cutting line is scored along the contour of theinner shape, at a first cutting station. The glass sheet is placed, forthis purpose, on a mat of felt type or of any other suitable type.

The glass sheet is then transferred by any suitable means to a break-outstation, more particularly to a support table 12 that forms bearingmeans for the glass sheet.

In the three examples from FIGS. 6a-8d , the table is provided withleaktight bearing seals 14, 16 arranged one around the other. A firstseal 14 is provided in order to be, after installation of the glasssheet, along and around the cutting line, on the outside with respect tothe cutting line. The outer seal 16 is for its part provided along andon the inside with respect to the outer contour of the peripheral shape10.

As a variant however, in particular as illustrated by the example fromFIGS. 9a-9d , the inner seal 14 is provided opposite the cutting line 2and thick enough to be in leaktight contact with the inner shape 6 andwith the peripheral shape 10. This is a variant that is also applicableto the examples from FIGS. 6a -8 c.

The inner seal 14 makes it possible to create a zone of low pressure(P⁻⁻) between the peripheral shape 10 and the support table 12, thusacting as convex bending means (see FIG. 6c ). A suction device is forexample incorporated into the support table for this purpose (notrepresented).

Owing to the additional presence of the outer seal 16, a partial vacuum(P⁻) may be created in the zone opposite the peripheral shape 10, so asto keep the peripheral shape flat, i.e. form a holding means thatcounters the bending deformation by the deformation means applied to theinner shape 6. A suction device (not represented) is also incorporatedinto the support table 12 for this purpose.

The outer seal is however optional should the peripheral shape 10 beheld mechanically, for example by applying a flat counter-form to theperipheral shape (variant not represented).

It should also be noted that, as a variant that is not represented, nomeans for keeping flat, in opposition to the convex bending deformation,is provided, in particular should the peripheral shape be of large sizeand the effect of gravity on the peripheral shape (or the effect ofgravity on the inner shape in the second embodiment) be sufficient toobtain the desired differential deformation between the inner shape 6and the peripheral shape 10.

In FIG. 6d , the inner shape 6 is kept bent without moving while theperipheral shape 10 is removed, for example by a suction table oranother means of any suitable type such as a mechanical means.

In the second example from FIGS. 7a to 7d , the break-out is achieved inthe same way as in the first example from FIGS. 6a-6d , but theextraction is carried out by removal of the inner shape 6 using asuitable suction table in order to keep the inner shape 6 bent duringthe extraction. It is thus understood that the convex bendingdeformation means is not necessarily the same as the means formaintaining the convex bending during the extraction. In this specificcase, the convex bending deformation means for the break-out is formedby the bearing seals 14, 16 and an associated suction device whilst themeans for maintaining the convex bending is formed by a suction tableprovided on the opposite side of the glass sheet, and preferably havinga convex counter-form 18 corresponding to the convexly bent inner shape.

The peripheral shape is still kept flat by suction.

In the third example from FIGS. 8a to 8d , the bending is carried outnot by suction but by mechanical bearing of a specific counter-form 18.The counter-form 18 has a shape corresponding to the convex shapedesired for the break-out, i.e. a suitable convex shape.

The extraction then takes place by suction of the inner shape onto theconvex counter-form 18 that was used for the break-out, thus forming ameans for maintaining the bending.

In the second embodiment illustrated by FIGS. 9a to 9d , the inner shapeis kept flat whilst the peripheral shape is deformed by convex bendingtoward the side opposite the cutting line 2.

In this example, the deformation means for the break-out is a suctionmeans, the support table 12 forming, between the two seals 14, 16, alow-pressure zone sufficient to deform the peripheral shape 10. Theinner shape 6 is itself subjected to a sufficient low-pressure zone forthe holding thereof in opposition to the bending deformation.

The extraction of the inner shape is carried out, for example, by asuction table, whilst the convex bending of the peripheral shape 10 ismaintained by suction.

It should be noted that, as a variant, in both embodiments, the bendingcould be carried out upward, for example if the glass sheet was held inthe air by suction. The cutting line 2 would in this case be on theunderside of the glass sheet.

The machine illustrated schematically in FIGS. 6a to 9d has at least onecomputer and one memory on which programs for controlling the machineare stored. The programs are suitable for controlling the machines fromFIGS. 6a to 9d , more particularly for controlling the cutting tool 6,and the bending deformation means, holding flat means and extractionmeans.

1. A process for breaking out an inner shape in a glass sheet intendedto form a glazing, comprising: scoring a cutting line in a surface ofthe glass sheet using a cutting tool, which cutting line delimits anouter contour of said inner shape and an inner contour of a peripheralshape; bringing the peripheral shape of the glass sheet into contactwith a bearing system along the outer contour of the inner shape;deforming, with a deformation system, one of the inner shape and of theperipheral shape by convex bending toward a side opposite the cuttingline, a differential deformation between the inner shape and theperipheral shape being sufficient to break out the inner shape along thecutting line and create a distance needed for a contactless extractionof the inner shape relative to the peripheral shape, the extractionbeing carried out while maintaining the convex bending.
 2. The processas claimed in claim 1, further comprising utilizing a holding systemthat counters the effect of the deformation system in the other of theinner shape and of the peripheral shape.
 3. The process as claimed inclaim 1, wherein the bearing system extends over an entire outer contourof the inner shape, inside, opposite or outside relative to the cuttingline.
 4. The process as claimed in claim 1, wherein the bearing systemcomprises two bearing members.
 5. The process as claimed in claim 1,wherein the bearing system comprises at least one seal for forming atleast one low-pressure zone opposite at least one of the inner shape andof the peripheral shape.
 6. The process as claimed in claim 5, wherein alow-pressure zone is a zone of convex bending deformation of said one ofthe inner shape and of the peripheral shape, the deformation systembeing a suction system.
 7. The process as claimed in claim 5, furthercomprising utilizing a holding system that counters the effect of thedeformation system in the other of the inner shape and of the peripheralshape, wherein a low-pressure zone is a holding zone that counters thedeformation of said other of the inner shape and of the peripheralshape, the holding system being a suction system.
 8. The process asclaimed in claim 1, wherein the bearing system is suitable for beingused for bearing against said other of the inner shape and of theperipheral shape during the breaking-out of the inner shape.
 9. Theprocess as claimed in claim 1, wherein the deformation system comprisesa convex counter-form suitable for pressing said one of the inner shapeand of the peripheral shape in convex bending.
 10. A machine forbreaking out an inner shape in a glass sheet intended to form a glazing,comprising: a cutting tool and a displacement system configured toautomatically displace said cutting tool in order to produce a cuttingline that delimits an outer contour of said inner shape and an innercontour of a peripheral shape; a bearing system configured to bearagainst the glass sheet along the outer contour of the inner shape; anda deformation system configured to deform one of the inner shape and ofthe peripheral shape by convex bending toward a side opposite thecutting line, and carrying out an extraction of the inner shape relativeto the peripheral shape while maintaining the convex bending of said oneof the inner shape and of the peripheral shape, with the deformationsystem and/or another system for maintaining the convex bending.
 11. Theprocess as claimed in claim 4, wherein the two bearing members arepositioned one around the other.